1. Field of the Invention
The present invention relates to a method of polishing a magnetic head slider including a thin film magnetic head element that performs recordation or reproduction of information on a recording medium such as a hard disk.
2. Description of the Related Art
In a magnetic recording apparatus such as a hard disk drive, a thin film magnetic head element that performs writing or reading of magnetic information is equipped in a magnetic head slider, which is provided opposing a recording surface of a recording medium such as a hard disk.
The magnetic head slider is hexahedral in shape and a couple of parallel slider rails is formed on one surface thereof. The surface of the slider rail is a surface opposing to the recording surface of the recording medium, which is called an air bearing surface (ABS) (or an airborne surface). A flow of air occurred between the recording surface and the air bearing surface by rotation of the recording medium makes the magnetic head slider slightly apart (popularly speaking, airborne) from the recording medium. The thin film magnetic head element is formed on the surface, which is hereinafter referred to as an element-formed surface, perpendicular to the air bearing surface.
As a method of forming the air bearing surface by polishing, Japanese Unexamined Patent Publication No. 132456/1995 discloses a method by which a disk-shaped board is rotated and an object to be polished is rocked along a diametral direction of the board, to polish the object to be polished. By this method, it is said that generation of scratches by polishing can be prevented by polishing the object to be polished under the condition that an average speed in the board-rotating direction is lower than a speed in the rocking direction in the latter half of the polishing process.
Generally, the thin film magnetic head element is formed on a predetermined substrate, having a multilayered structure including various kinds of insulating layers, magnetic layers and the like. But the substrate and the element structural materials are different in hardness of materials. Consequently, it is known that performing a polish on a element-multilayered end face, which is parallel to a direction of stacking of thin films, of the magnetic head slider in order to form the air bearing surface causes a by-processed step on the polished surface. More specifically, because the element structural materials are softer than the substrate, a portion of the element-multilayered end face on the air bearing surface becomes recessed, in other words, lower than a portion of the substrate section. As a result, when the magnetic head slider is actually equipped in the hard disk drive, a distance between the multilayered section portion of the thin film magnetic head element and the surface of the disk cannot be sufficiently shortened, and it is difficult to improve a strength of a signal magnetic field for recording and reproducing.
In the above polishing method, the by-processed step on the air bearing surface is not considered in the least, and it is conceivable that the by-processed step on the air bearing surface cannot be reduced.
On the other hand, some polishing methods are proposed with the aim of reducing such a by-processed step.
For example, Japanese Unexamined Patent Publication No. 134316/1998 and Japanese Unexamined Patent Publication No. 245333/1997 disclose a method of polishing a magnetic head, in which method a pretreatment to embed abrasive in the board is performed according to a predetermined procedure with correcting ring and dummy work, and the board performed with the pretreatment is rotated, with a solution including no abrasive dropped down on the board.
Japanese Unexamined Patent Publication No. 180389/1997 discloses a method of polishing an airborne surface (air bearing surface) of a magnetic head slider with a lap which is equipped with a main body of the lap in plate shape and abrasive particles fixed on the surface of the main body of the lap. The abrasive is embedded, of which a part is exposed.
Japanese Unexamined Patent Publication No. 84657/1993 discloses a method of polishing an airborne surface of a magnetic head with a lap and a mixed solution of an anion surface-active agent and an amphoteric surface-active agent. The lap is made of a material that combines a phase of tin with a phase of brass possessing greater stiffness for supporting abrasive than tin.
However, in each of the above technologies the rotation speed of the polishing plate is not taken into consideration, although reduction of a by-processed step is intended in common.
The invention has been achieved in light of the foregoing problems and its object is to provide a method of polishing a magnetic head slider, by which the height of a by-processed step on an element-multilayered end face (a surface to be polished) of the magnetic head slider is easily reduced and thereby a polish with high accuracy is enabled.
A method of polishing the magnetic head slider according to the first aspect of the invention is a method of polishing a magnetic head slider, whereby an element-multilayered end face of the magnetic head slider where a thin film magnetic head element is formed as a multilayered structure is polished with a polishing plate having a polishing surface, including: a first polishing step of polishing the element-multilayered end face of the magnetic head slider by means of setting the polishing plate to rotate at a first velocity; and a second polishing step of performing a finishing polish of the element-multilayered end face of the magnetic head slider processed in the first polishing step by means of setting the polishing plate to rotate at a second velocity lower than the first velocity, wherein the second velocity is set so that an average linear velocity in a direction of the rotation of the polishing plate is equal to or lower than 0.032 meters per second in the second polishing step. In the second polishing step, the magnetic head slider may be set to reciprocate along a direction almost orthogonal to the direction of the rotation of the polishing plate.
In the method of polishing the magnetic head slider according to the first aspect of the invention, the first polishing step is performed by means of the polishing plate rotating at the first velocity, and the second polishing step is performed by means of the polishing plate rotating at the second velocity lower than the first velocity. The second velocity is set so that the average linear velocity in the direction of the rotation of the polishing plate is equal to or lower than 0.032 meters per second.
In a method of polishing a magnetic head slider according to the second aspect of the invention, is the element-multilayerd end face of the magnetic head slider where the thin film magnetic head element is formed as a multilayered structure is polished with the polishing plate having the polishing surface, including the first polishing step of polishing the element-multilayered end face of the magnetic head slider by means of setting the polishing plate to rotate at the first velocity; and the second polishing step of performing the finishing polish of the element-multilayered end face of the magnetic head slider processed in the first polishing step by means of setting the magnetic head slider to reciprocate along the direction almost orthogonal to the direction of the rotation of the polishing plate in the first polishing step with the polishing plate set to stop.
In the method of polishing the magnetic head slider according to the second aspect of the invention, the first polishing step is performed by means of the polishing plate rotating at the first velocity, and the second polishing step is performed by means of setting the magnetic head slider to reciprocate along the direction almost orthogonal to the direction of the rotation of the polishing plate at the first polishing step with the polishing plate set to stop.
In the method of polishing a magnetic head slider according to the first aspect of the invention, it is preferable that the second velocity is set so that the average linear velocity in the direction of the rotation of the polishing plate is equal to or lower than 0.008 meters per second in the second polishing step.
Furthermore, in the method of polishing the magnetic head slider according to the first or the second aspect of the invention, it is preferable to perform the second polishing step using a polishing liquid that includes no polishing particles. Furthermore, it is preferable to perform the first polishing step using a polishing liquid that includes polishing particles. It is preferable that the first polishing step and the second polishing step are set to be continuously performed with one and the same polishing apparatus.
In a method of polishing a magnetic head slider according to the third aspect of the invention, a cleaning step for removing the impurities generated in the first polishing step is performed before starting the second polishing step. In this polishing method, an effect that the impurities have on the second polishing step is reduced, because almost all the impurities are removed before starting the second polishing step. Here, the impurities include the polishing abrasives used at the first polishing step, polish leavings newly produced at the first polishing step and the other matter.
In the method of polishing a magnetic head slider according to the third aspect of the invention, the impurities may be removed by means of wiping off the impurities on the polishing plate with a predetermined solvent in the cleaning step. Otherwise, the impurities on the polishing plate may be removed using a member for removing the impurities that is provided on the polishing surface of the polishing plate while the polishing plate is rotated with a predetermined solvent being supplied in the cleaning step. It is preferable that the first polishing step, the cleaning step and the second polishing step are continuously performed with one and the same polishing apparatus.
Other and further objects, features and advantages of the invention will appear more fully from the following description.